遅ミオセンの大気中のCO2濃度とC2草の広がり
1Department of Geosciences, The Pennsylvania State University, University Park, PA 16872, USA.
まとめ
前述の理論に反して,大気中の二酸化炭素 (CO2) はミオセンの末期に減少しなかった. 代わりに,C4の草原の拡大は,干ばつと降雨パターンの変化によって引き起こされた可能性が高い.
科学分野:
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- パレオボタニーは古植物学です.
- 地質化学 地質化学
背景:
- ミオセンの末期におけるC4草原の拡大は,以前は大気中の二酸化炭素 (CO2) レベルが低下したことに起因していた.
- この仮説は,二酸化炭素の変化に関する直接的な証拠の欠如と,植物分布に対する他の環境要因の知られている影響のために議論されています.
研究 の 目的:
- ミオセンのC4期後半の草原の拡大を促すCO2 (pCO2) の大気部分圧の役割を調査する.
- ミオセンの末期におけるpCO2変動の直接的な証拠を提供するためである.
主な方法:
- アルケノンベースの地化学プロキシを用いて,過去の大気中のpCO2レベルを再構築した.
- 14~9百万年前のpCO2変化のタイムラインを確立するために堆積物核を分析しました.
主要な成果:
- アルケノンベースのpCO2の推定では,1400万年前から900万年前に増加し,その後,工業化以前の水準で安定した.
- ミオセンの後半期のpCO2の大幅な減少の有意な証拠は見つかりませんでした.
結論:
- C4草原のミオセンの後半の拡大は,大気中のCO2の減少によって引き起こされなかった.
- 干ばつの増加や降雨パターンの変化などの代替要因は,より重要な役割を果たした可能性があります.
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